My affair was with a coworker.
My job isn't a corporate or office environment, so in my case "coworker" simply means that we work at the same place. Everyone's work is very independent of each other. I have heard the term "work spouse" before but it has never applied to any environment I've ever been a part of.
It has been a problem for me, the choosing to date people I work with. All of my relationships but two have been with people I've met at work (different jobs over the years). XH is also a coworker.
If it should ever not work out with him, I need to be done dating men I work with. Me: XWS, 30s, 5-month EA/PA in '09-'10
Husband: XBS, 40s
Married 2.5 years